ABNORMAL PRESSURE BELTS AND HYDROCARBON ACCUMULATION MODELS IN THE LISHUI SAG,THE DONGHAI BASIN

It is proved by well data that abnormal high-pressure exists widely in the Paleogene Mingyuefeng Formation of the Lishui Sag,the Donghai Basin.In this paper,the geologic,drilling,logging and testing data are synthesized,the types,genetic mechanism and characteristics of abnormal high-pressure in the Lishui Sag are studied,and the control action of abnormal high-pressure to hydrocarbon migration and accumulation,pool-forming mechanism and hydrocarbon distribution rules is analysed.At last,three models of hydrocarbon accumulation under abnormal high-pressure are summarized,that is,the sandstone accumulation model above abnormal high-pressure sealing layers,the accumulation model within overpressure layers and the accumulation model under sealing layers.These models have important directive significance to hydrocarbon exploration and development.